1. Field of the Invention
This invention relates in general to gondola rail cars and more particularly, to the attachment of the center sill of a gondola car to its concave floor panels, often referred to as tubs.
2. Summary of the Prior Art
Gondola rail cars are commonly used to carry bulk materials, such as coal, sand, gravel or the like. One type of gondola car employs concave floor panels which significantly increase the load carrying volume of the car beneath the center sill. An example of a railway gondola car having concave floor panels is disclosed in U.S. Pat. No. 4,361,097 issued Nov. 30, 1982 to Jones et al. The gondola car shown in the Jones et al patent includes concave floor panels disposed on each side of the center sill to form longitudinally extending tubs which extend beneath the center sill for increased capacity. The double tubs of the foregoing Jones et al patent are affixed at their inner edges by welds or rivets to the center sill. During operation of such prior gondola cars, the stresses imposed upon the center sill are transmitted to the concave floor panels to cause potential fatigue cracking of the tub material over a period of time. Accordingly, it is desirable to provide an improved technique by which the tubs are attached to the center sill to minimize the occurrence of fatigue cracking.